Spark plug



June 17, 1924.

. H. A. RASMUSSEN S PARK PLUG Filqd Sept; 2.9, 1920 Patented June 17, 1924.

o A 1,497,985 umrzo STATES PATENT OFFICE.

HARRY A. RASMUSSEN, OI MOLINE, ILLIN'OTS.

srnnx PLUG.

Application filed September 29, 1920. Serial Ho. 413,479.

2' '0 all whom it may concern:

Be it knownthat I, HARRY A. RAsMUssEN,

a citizen of the United States, residing at Moline, in the county of Rock Island and.

State of Illinois, have invented certain new and useful Improvements in Spark Plugs,

'of which the following is a specification.

This invention relates to spark plugs, and

it comprises an outer shell, insulation of porcelain or other suitable material arranged within the shell, and a central electrode arranged with said insulation and projecting .below the lower endof the insulation, said electrode being provided with a cup-like member surrounding the bottom of the in sulation, and a baflie arranged below said cup-like member and spaced therefrom.

One of the most serious objections to spark plugs as at present manufactured is the tendency of carbon, or oil and dirt, to accumulate in the firing chamber at the bottom of the plug and settle on the surface of the insulation, causing shortcircuiting. When considerable carbon collects on the insulation and this carbon is mixed with oil, it forms a conductor between the central electrode and the outer shell which permits the current to pass from thecentral electrode to the outer shell without passing the chamber at the bottom of the plug sparking gap and igniting the gas.

, In the present invention, I have produced a foulless spark plug wherein the firing is made considerably larger to aid ignition and prevent entrance of carbon an wherein the central electrode is provided with a substantially conical sha e bafile to dirt into the firing chamber. The lower end of the insulation which is a point where the greatest accumulation of carbon and other forei substances generall occur, is surrounde by a cup shaped mem r and thereby rotected so as to eliminate deposits of 'car on.

In the accom anying drawings, I have shown one embo iment of theinvention. In

this showing,

Figure 1 is a central vertical sectional view. I

Figure-2 is a perspective-view of the central electrode, and I Figure 3 is a horizontal sectional view on the line 3-3 of Figure 1.

Referring to the drawings, the reference numeral 1 designates the outer shell which is provided with the usual screw threaded portion-2, whereby the plug is inserted in v the outer electrode.

the cylinder. The top of the shell is slightly enlarged formin a shoulder 3 which receives the insulatlon 4 of porcelain. or other suitable material and prevents displacement thereof in a downward direction. A nut 5 is adapted to maintain the porcelain insulation in position in the usual manner. An outer electrode'6 is, arranged on the bottom of the shell near the openings 7. The porcelain insulation is adapted to receive the central electrode 8 which is screw threaded at its upper end for the reception of a nut 9 tical flanges 15 forming a cup-like member surrounding the lower end of the insulation. Between the cup-like member and the lower end of the electrode, there is provided a substantially conical shaped baflle plate 16 secured to the electrode.

7 The construction heretofore described is a very efiicient type of spark plug in" that the point where the accumulation of carbon and other foreign matter is generally greatest, the point where the electrode enters the insulation, is protected by the cup-like member surrounding it and the introduction of carbon and other foreign matter into the firing chamber is practically eliminated by the baffle plate 16.

It is to be understood that while I have described the preferred embodiment of in- I vention, variousv changes in the-shape, size, and arrangement of parts may be resortedto without departing from the spirit of the iilivention or the scope of the subjoined 0 mm.

Having thus described my invention,- I.

claim: 1

A spark plug comprising an outer shell, the lower end of said shell being provided with a relatively small opening, a body of insulation arranged in the upper portionof' said shell, said insulation eing provided with a central opening having an enlargement at its lower end,'an.electrode arranged plate being of larger diameter than said in said opening, a collar carried by said opening. 10

, electrode and arranged in said enlar ement, In testimon whereof I aflix m si ature a. cup shaped member arranged on-sa1d elecin presence 0 two witnesses. I

"6 trode and surrounding the lower end of said HARRY A. RASMUSSEN. insulation, and a conical shaped bafiie plate Witnesses:

secured to said electrode between said on ALBERT H. RAsMUssEN,

, shaped member and said opening, said ba e ELENORA V. RABMUSSEN. 

